net.sf.saxon.event

## Class NamespaceReducer

- java.lang.Object
- - net.sf.saxon.event.SequenceReceiver
  - - net.sf.saxon.event.ProxyReceiver
    - - net.sf.saxon.event.NamespaceReducer

- All Implemented Interfaces:
    Result, Receiver, NamespaceResolver

      public class NamespaceReducer
      extends ProxyReceiver
      implements NamespaceResolver

  NamespaceReducer is a ProxyReceiver responsible for removing duplicate namespace declarations. It also ensures that an xmlns="" undeclaration is output when necessary. Used on its own, the NamespaceReducer simply eliminates unwanted namespace declarations. It can also be subclassed, in which case the subclass can use the services of the NamespaceReducer to resolve QNames.

  The NamespaceReducer also validates namespace-sensitive content.

- - ### Field Summary

    - ### Fields inherited from class net.sf.saxon.event.ProxyReceiver

      `nextReceiver`

    - ### Fields inherited from class net.sf.saxon.event.SequenceReceiver

      `pipelineConfiguration, previousAtomic, systemId`

    - ### Fields inherited from interface javax.xml.transform.Result

      `PI_DISABLE_OUTPUT_ESCAPING, PI_ENABLE_OUTPUT_ESCAPING`

  - ### Constructor Summary

    Constructors
    Constructor and Description
    `NamespaceReducer(Receiver next)` Create a NamespaceReducer

  - ### Method Summary

    Methods
    Modifier and Type | Method and Description
    --- | ---
    `void` | `endElement()` endElement: Discard the namespaces declared on this element.
    `String` | `getURIForPrefix(String prefix, boolean useDefault)` Get the namespace URI corresponding to a given prefix.
    `Iterator<String>` | `iteratePrefixes()` Get an iterator over all the prefixes declared in this namespace context.
    `void` | `namespace(NamespaceBinding namespaceBinding, int properties)` Output a namespace node (binding)
    `void` | `startContent()` startContent: Add any namespace undeclarations needed to stop namespaces being inherited from parent elements
    `void` | `startElement(NodeName elemName, SchemaType typeCode, int locationId, int properties)` startElement.

    - ### Methods inherited from class net.sf.saxon.event.ProxyReceiver

      `append, attribute, characters, close, comment, endDocument, getNamePool, getUnderlyingReceiver, open, processingInstruction, setPipelineConfiguration, setSystemId, setUnderlyingReceiver, setUnparsedEntity, startDocument, usesTypeAnnotations`

    - ### Methods inherited from class net.sf.saxon.event.SequenceReceiver

      `append, getConfiguration, getPipelineConfiguration, getSystemId`

    - ### Methods inherited from class java.lang.Object

      `clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait`

- - ### Constructor Detail

    - #### NamespaceReducer

          public NamespaceReducer(Receiver next)

      Create a NamespaceReducer
      Parameters:
        `next` - the Receiver to which events will be passed after namespace reduction

  - ### Method Detail

    - #### startElement

          public void startElement(NodeName elemName,
                          SchemaType typeCode,
                          int locationId,
                          int properties)
                            throws XPathException

      startElement. This call removes redundant namespace declarations, and possibly adds an xmlns="" undeclaration.
      Specified by:
        `startElement` in interface `Receiver`
      Overrides:
        `startElement` in class `ProxyReceiver`
      Parameters:
        `elemName` - integer code identifying the name of the element within the name pool.
        `typeCode` - integer code identifying the element's type within the name pool.
        `locationId` - an integer which can be interpreted using a `LocationProvider` to return information such as line number and system ID. If no location information is available, the value zero is supplied.
        `properties` - properties of the element node
      Throws:
        `XPathException` - if an error occurs

    - #### namespace

          public void namespace(NamespaceBinding namespaceBinding,
                       int properties)
                         throws XPathException

      Output a namespace node (binding)
      Specified by:
        `namespace` in interface `Receiver`
      Overrides:
        `namespace` in class `ProxyReceiver`
      Parameters:
        `namespaceBinding` - the prefix/uri pair to be output
        `properties` - the properties of the namespace binding
      Throws:
        `XPathException` - if any downstream error occurs

    - #### startContent

          public void startContent()
                            throws XPathException

      startContent: Add any namespace undeclarations needed to stop namespaces being inherited from parent elements
      Specified by:
        `startContent` in interface `Receiver`
      Overrides:
        `startContent` in class `ProxyReceiver`
      Throws:
        `XPathException` - if an error occurs

    - #### endElement

          public void endElement()
                          throws XPathException

      endElement: Discard the namespaces declared on this element.
      Specified by:
        `endElement` in interface `Receiver`
      Overrides:
        `endElement` in class `ProxyReceiver`
      Throws:
        `XPathException` - if an error occurs

    - #### getURIForPrefix

          public String getURIForPrefix(String prefix,
                               boolean useDefault)

      Get the namespace URI corresponding to a given prefix. Return null if the prefix is not in scope.
      Specified by:
        `getURIForPrefix` in interface `NamespaceResolver`
      Parameters:
        `prefix` - the namespace prefix
        `useDefault` - true if the default namespace is to be used when the prefix is ""
      Returns:
        the uri for the namespace, or null if the prefix is not in scope

    - #### iteratePrefixes

          public Iterator<String> iteratePrefixes()

      Get an iterator over all the prefixes declared in this namespace context. This will include the default namespace (prefix="") and the XML namespace where appropriate
      Specified by:
        `iteratePrefixes` in interface `NamespaceResolver`
      Returns:
        an iterator over all the prefixes for which a namespace binding exists, including the zero-length string to represent the null/absent prefix if it is bound

Copyright (c) 2004-2013 Saxonica Limited. All rights reserved.